Ester Formation Research Articles

Thin layer chromatography of methylated derivatives of sodium alkylbenzenesulfonates in water analysis by GC-MS

Sodium alkylbenzene sulfonates or linear alkyl benzene sulfonates (LAS) are the most common synthetic anionic surfactants and water pollutants. They can cause both acute and chronic toxic effects on water organisms. Selective determination of sodium alkylbenzene sulfonates as a separate class of anionic surfactants is possible using gas chromatography coupled with mass spectrometry (GC-MS) in the form of linear alkylbenzenesulfonic acid methyl esters (LABSA ME). In order to purify the extracts and concentrate the analytes, we studied the behaviour of these compounds by ascending high-performance thin-layer chromatography using Kieselgel 60 F254 and Sorbfil plates. A mixture of n-hexane and methanol solvents in a ratio of 23:1 (by volume) was used as the mobile phase. Under these conditions, sodium alkylbenzenesulphonates remain on the start line, while their derivatives (ME ABSC), obtained by methylation with trimethyl orthoformate in the presence of trifluoroacetic acid (with a yield of η=98%), form zones characterised by retention coefficient values of Rf = 0.62 and Rf = 0.71 on Kieselgel 60 F254 and Sorbfil plates, respectively. The repeatability of the Rf values was characterised by a standard deviation of 6.1 and 5.9 %, respectively (n=16). The completeness of extraction (95.0–100.0 %) of analytes from the plates by descending TLC with acetonitrile was noted. The applicability of the TLC method for the concentration of analytes and pretreatment of extracts on the example of real water samples was shown. Using GC-MS with electron impact ionisation, we determined the concentrations of sodium alkylbenzenesulphonates in water sampled in the southern basin of Lake Baikal from a depth of 400 m (0.24±0.02 µg/dm3) and in snowmelt water from the ice of the Krestovka River where it flows into Lake Baikal near the village of Listvyanka (31.1 ± 1.0 µg/dm3).

Retrospective Data Analysis Reveals Unusual Metabolism Pattern of Ethanol in Pediatrics as Compared to Adult and Geriatric Populations.

About 95% of consumed ethanol is metabolized by oxidative pathways. Less than 1% is metabolized via nonoxidative pathways: glucuronidation, sulfation, and the formation of fatty acid esters of ethanol. In neonates, the glucuronidation pathway has been reported to be underdeveloped but matures with age. This work compared the test results of patients' random urine samples submitted to our facility for ethyl glucuronide (EtG) and ethyl sulfate (EtS) measurements across pediatric and adult populations. Test results (n = 63 498) from urine samples tested for EtG and EtS by quantitative liquid chromatography-tandem mass spectrometry at our facility were utilized for this study. EtG and EtS concentrations were compared across the age partitions 0 to 17 years (pediatric), 18 to 80 years (adult), and 81 to 100 years (geriatric). Eight pediatric patients from a tertiary academic hospital contributed clinical context via abstracted clinical information. Across the individual age partitions, 60% to 65% of patients had both EtG and EtS present in urine. Approximately 5% to 10% of patients had only EtG, and 25% to 35% had neither metabolite present. The lowest percentages (<1.5%) had EtS present in the absence of EtG. Markedly, no pediatric patients had only EtS present; compared to the adult population, this was statistically significant (Fisher exact test, P = 0.025). From the data presented in this work, EtG is more prevalent relative to EtS in urine samples of patients assessed for ethanol exposure.

Bioavailability of Lutein from Marigold Flowers (Free vs. Ester Forms): A Randomised Cross-Over Study to Assess Serum Response and Visual Contrast Threshold in Adults.

Lutein (Lut) and zeaxanthin (Zeax) are found in the blood and are deposited in the retina (macular pigment). Both are found in the diet in free form and esterified with fatty acids. A high intake and/or status is associated with a lower risk of chronic diseases, especially eye diseases. There is a large global demand for Lut in the dietary supplement market, with marigold flowers being the main source, mainly as lutein esters. As the bioavailability of Lut from free or ester forms is controversial, our aim was to assess the bioavailability of Lut (free vs. ester) and visual contrast threshold (CT). Twenty-four healthy subjects (twelve women, twelve men), aged 20-35 and 50-65 years, were enrolled in a cross-sectional study to consume 6 mg lutein/day from marigold extract (free vs. ester) for two months. Blood samples were taken at baseline and after 15, 40, and 60 days in each period. Serum Lut and Zeax were analysed using HPLC, and dietary intake was determined with a 7-day food record at the beginning of each period. CT, with and without glare, was at 0 and 60 days at three levels of visual angle. Lut + Zeax intake at baseline was 1.9 mg/day, and serum lutein was 0.36 µmol/L. Serum lutein increased 2.4-fold on day 15 (up to 0.81 and 0.90 µmol/L with free and ester lutein, respectively) and was maintained until the end of the study. Serum Zeax increased 1.7-fold. There were no differences in serum Lut responses to free or ester lutein at any time point. CT responses to lutein supplementation (free vs. ester) were not different at any time point. CT correlated with Lut under glare conditions, and better correlations were obtained at low frequencies in the whole group due to the older group. The highest correlations occurred between CT at high frequency and with glare with serum Lut and Lut + Zeax. Only in the older group were inverse correlations found at baseline at a high frequency with L + Z and with Lut/cholesterol and at a low frequency with Lut/cholesterol. In conclusion, daily supplementation with Lut for 15 days significantly increases serum Lut in normolipemic adults to levels associated with a reduced risk of age-related eye disease regardless of the chemical form of lutein supplied. Longer supplementation, up to two months, does not significantly alter the concentration achieved but may contribute to an increase in macular pigment (a long-term marker of lutein status) and thus improve the effect on visual outcomes.

Abstract 1025: Structural Basis Of Apolipoprotein A1 Activation Of Lecithin:Cholesterol Acyl Transferase In High Density Lipoproteins

Lecithin:cholesterol acyl transferase (LCAT) is responsible for the formation of extracellular cholesteryl ester, which is critical for high density lipoprotein (HDL) maturation. It also modulates numerous HDL physiological functions by impacting particle subspeciation patterns. LCAT is activated by apolipoprotein A1 (APOA1) which forms antiparallel dimers around the edge of nascent HDL. Previous work has suggested that the interface of APOA1 helices 4 and 6, when properly aligned, creates two symmetrical sites for productive LCAT binding. Size exclusion chromatography was used to isolate reconstituted HDL discs containing two molecules of APOA1 chemically crosslinked to 2 LCAT molecules. Mass spectrometry using multiple crosslinkers, including a novel application of formaldehyde, indicated that LCAT interacts with both APOA1 helices 4 and 6. Cryo-electron microscopy (cryoEM) was used to determine a 10 Å structure of the complex. Using the HADDOCK suite of molecular docking tools, we developed a structural model of LCAT bound to APOA1 discs that is consistent with the preponderance of data accumulated so far. The model shows that LCAT may bind at the two symmetrical sites in different orientations, possibly reflecting different steps of the LCAT reaction. Work to improve the resolution of the cryoEM datasets is ongoing. Further work, using strategically designed cysteine mutations in APOA1 to lock helices 4 and 6 together, suggests that the helices do not move apart during the LCAT reaction process. Determination of the structural interactions between LCAT and its activator, APOA1, is crucial to understanding HDL maturation, which has significant clinical implications. This work provides the highest resolution structural model available for this important interaction.

Influence of dielectric barrier discharge plasma processing in the volatile compounds and aroma of cashew apple juice

Cashew apple juice is a popular beverage in several parts of the world due to its unique fruity aroma. However, the high styrene concentration contributes to an undesirable balsamic note. To address this issue, cold plasma technology was proposed to alter the juice's volatile compounds, thereby improving its flavor. This study has evaluated the effects of cold plasma on the volatile compounds and aroma of cashew apple juice. The research was conducted by applying dielectric barrier discharge plasma to the juice, varying the frequency (50–1000 Hz) and processing times (5–20 min) while keeping a constant voltage (18 kV). The plasma treatment induced noteworthy changes in the volatile compounds of the juice. Specifically, there was a significant decrease in volatile organic acids (73%) and an increase in aldehydes (52%), alcohols (67%), and short-chain esters (11%). Plasma induced the internal scission of fatty acids and esters, which resulted in the formation of short-chain esters and aldehydes. Further processing has oxidized the aldehydes, generating alcohols and isomerized short-chain esters, which generate branched esters. Cold plasma, however, did not significantly reduce the styrene concentration and could not mitigate the off-flavor caused by this compound.

Analysis of biodiesel process from waste cooking oil using heterogeneous catalyst field snail shell (pila ampullacea)

Biodiesel is an alternative fuel in the form of Fatty Acid Methyl Ester (FAME) which can be renewed using vegetable oils and animal oils through esterification or transesterification processes. This study used waste cooking oil as a raw material for biodiesel with a CaO catalyst from the shells of field snails (Pila ampullacea) which were calcined for 4 hours at a temperature of 700°C. This experiment aim to study of the effect of temperature (55°C, 60°C, 65°C) and catalyst weight (4%, 6%, 8%), for 2 hours the transesterification process and the molar ratio of oil to methanol was 1:9. Crude Biodiesel from the transesterification process washed using dry washing method with activated coconut shell charcoal which has been activated using 1M H3PO4. Based on this research, the optimum yields about 91,5%-volume, were obtained in A2T2 with temperature 60°C and a catalyst weight of 6% with a biodiesel yield of 91.5%. The characteristics of the biodiesel produced were kinematic viscosity 3.32 cSt, density 863 Kg/m3, acid number 0.543%, iodine number 14.3%-mass, methyl ester content 169.12% and cetane number 43.28%-mass.

Impact of Zwitterions on the Acidity Constant and Glucose Sensitivity of Block Copolymers with Phenylboronic Acid.

Molecular assemblies that transform in response to pH and saccharide concentration are promising nanomaterials in the field of biomedicine, and polymeric micelles of amphiphilic polymers with phenylboronic acids (PBAs) have been studied. Herein, we report the impact of zwitterions on the acidity constant for the collapse and the glucose sensitivity of a polymeric micelle produced from a diblock copolymer comprising polyacrylamides with PBA and zwitterionic carboxybetaine (PAEBB-b-PCBAAm). The diblock copolymer was synthesized through reversible addition-fragmentation chain-transfer polymerization followed by deprotection. PAEBB-b-PCBAAm produced micellar aggregates in aqueous solutions at a neutral pH, and the polymeric micelles collapsed at a pH of 11.0 because the PBA transformed into a hydroxyboronate anion. The pKa decreased in the presence of glucose owing to boronate ester formation. The PCBAAm chain significantly increased the pH at which the molecular assemblies dissociated. This is probably because the pKa of boronic acid increased through the dipolar interaction of zwitterions, and/or the zwitterionic polymer corona is valid for screening of PBA ionization and electrostatic repulsion of boronate anions. This study on the modulation of pKa through the zwitterionic interaction can facilitate the molecular design of pH- and saccharide-responsive biomaterials.

Effect of amylose partial extraction on citrate esterification of potato starch and its role in structure and physicochemical modification

This study examines the impact and influence of amylose on the starch esterification reaction through partial extraction of amylose. Citric acid was added for the esterification reaction, and then the esterified starches' multiscale structure, physicochemical, and functional properties were evaluated. As the extraction time of amylose increased, the amylose content in the starch decreased. Higher concentrations of citric acid will lead to samples with a higher degree of substitution, with DS rising from 0.203 % (0 h) to 0.231 % (3.5 h) at CA3 treatment. While removing amylose had minimal effects on the crystal structure of starch granules, it did decrease the ratio of A and B1 chains and the molecular weight of amylose. Acid hydrolysis exacerbated these changes upon the addition of citric acid. Furthermore, removing amylose followed by citrate esterification resulted in lower pasting viscosity, enthalpy of gelatinization (from 13.37 J to 2.83 J), and degree of short-range ordering. Also, digestion shows a decrease caused by the increasing content of slow-digesting starch. The presence of amylose in starch granules does affect the formation of starch esters, and removing it before esterification modification may improve production efficiency and reduce costs to some extent.

A Concise, Practical Chiral Resolution Approach of Racemic (E)-4,4-Dimethyl-1-(4-nitrophenyl)pent-1-en-3-ol to Its both Enantiomers via Strategy of Diastereomeric Ester Formation and Crystallization Using both N-Boc-D- and N-Boc-L-phenylglycines as Chiral Auxiliaries

A Concise, Practical Chiral Resolution Approach of Racemic (E)-4,4-Dimethyl-1-(4-nitrophenyl)pent-1-en-3-ol to Its both Enantiomers via Strategy of Diastereomeric Ester Formation and Crystallization Using both N-Boc-D- and N-Boc-L-phenylglycines as Chiral Auxiliaries

Two-stage co-pyrolysis of Kraft lignin and palm oil mixture to biofuels: The role of lignin as a methylation agent for methyl ester formation

In this work pyrolysis of palm oil and lignin has been investigated using a two-stage process at 550 °C, with a first step configuration of continuous condensation for vapors and separation of gases, and a second step with distillation of vapors. Experiments were realized as pyrolysis of palm oil, palmitic acid, and Kraft lignin, as well as co-pyrolysis of palm oil/lignin, palmitic acid/lignin and palmitic acid/guaiacol. It has been shown that the addition of lignin improves the quality of palm oil pyrolysis bio-oil, thanks to the conversion of fatty acids coproduct to fatty acid methyl esters (FAME). The production of methyl esters in the reaction environment using palm oil and lignin was studied by conducting experiments with palmitic acid and lignin, as well as palmitic acid and guaiacol (the main product obtained from lignin pyrolysis). The results highlighted that during pyrolysis, the production of FAME is a consequence of a direct esterification reaction on palmitic acid. The formation of FAMEs during pyrolysis presents a promising avenue to optimize the utilization of palm oil by generating FAMEs as supplementary fuel products, Furthermore, it is possible to consider the application of the studied process for the conversion of free fatty acids into FAME.

Saccharomyces cerevisiae cellular engineering for the production of FAME biodiesel

The unsustainable and widespread utilization of fossil fuels continues to drive the rapid depletion of global supplies. Biodiesel has emerged as one of the most promising alternatives to conventional diesel, leading to growing research interest in its production. Microbes can facilitate the de novo synthesis of a type of biodiesel in the form of fatty acid methyl esters (FAMEs). In this study, Saccharomyces cerevisiae metabolic activity was engineered to facilitate enhanced FAME production. Initially, free fatty acid concentrations were increased by deleting two acetyl-CoA synthetase genes (FAA1, FAA4) and an acyl-CoA oxidase gene (POX1). Intracellular S-adenosylmethionine (SAM) levels were then enhanced via the deletion of an adenosine kinase gene (ADO1) and the overexpression of a SAM synthetase gene (SAM2). Lastly, the S. cerevisiae strain overproducing free fatty acids and SAM were manipulated to express a plasmid encoding the Drosophila melanogaster Juvenile Hormone Acid O-Methyltransferase (DmJHAMT). Using this combination of engineering approaches, a FAME concentration of 5.79 ± 0.56 mg/L was achieved using these cells in the context of shaking flask fermentation. To the best of our knowledge, this is the first detailed study of FAME production in S. cerevisiae. These results will provide a valuable basis for future efforts to engineer S. cerevisiae strains for highly efficient production of biodiesel.

Genome-Driven Discovery of Hygrocins in Streptomyces rapamycinicus.

Ansamycins, represented by the antituberculosis drug rifamycin, are an important family of natural products. To obtain new ansamycins, Streptomyces rapamycinicus IMET 43975 harboring an ansamycin biosynthetic gene cluster was fermented in a 50 L scale, and subsequent purification work led to the isolation of five known and four new analogues, where hygrocin W (2) belongs to benzoquinonoid ansamycins, and the other three hygrocins, hygrocins X-Z (6-8), are new seco-hygrocins. The structures of ansamycins (1-8) were determined by the analysis of spectroscopic (1D/2D NMR and ECD) and MS spectrometric data. The Baeyer-Villiger enzyme which catalyzed the ester formation in the ansa-ring was confirmed through in vivo CRISPR base editing. The discovery of these compounds further enriches the structural diversity of ansamycins.

Co-pyrolysis characteristic of sugarcane waste with polyethylene terephthalate: thermal decomposition, product distribution, synergistic effect, and kinetics analysis.

This work has focused on the co-pyrolysis of sugarcane waste (SW) with polyethylene terephthalate (PET) to gain insight on its thermal decomposition, product distribution, kinetics, and synergistic effect. SW and PET were blended at different ratios (100:0, 80:20, 60:40, 40:60, and 0:100), and the Coats-Redfern method was used to determine the kinetics parameters. To ascertain the synergistic effect between SW and PET, product yields and composition of chemicals were compared with the synergistic effect of the individual components of pyrolysis. The bio-oil yield was significant at 60% of PET, with a difference of 19.41 wt% compared to the theoretical value. The synergistic impact of SW:PET on ester formation and acid compound inhibition was the most dominant at the 60:40 ratio. The kinetics analysis revealed that the diffusion mechanism, power law, and order of reactions were the most probable reaction models that can explain the pyrolysis of SW, and PET, and their blends. The resultant co-pyrolysis oil contained slightly larger hydrogen and carbon contents with low oxygen, and sulphur, and nitrogen contents, which improved the quality of the bio-oil. The results of this work could be used as a guide in selecting proper reaction conditions with optimal synergy during the co-pyrolysis process.

Electrochemical Alchemy: Novel NH2@Pt/AgVO3 and boronic acid recognition to probe insulin-resistant macrophage phenotype shifts via glucose analysis and DFT studies

Glucose is a known energy source that gives insights into cellular metabolism by glycolysis, biosynthesis and glycogen for storage. Investigation of glucose uptake in immune cells requires highly expensive tags and imaging techniques, however, we developed an amine (NH2) nobbled Platinum (Pt)-Silver vanadate (AgVO3) sensor platform combined with 3-mercapto phenylboronic acid (MPBA) recognition element for an enzyme-free glucose sensor. Introducing the amine groups into the Pt surface protects the stability of the Pt and extends the longevity of the electrode. A slightly acidic pH-driven boronate ester formation between glucose and boronic acid mechanism and the glucose combined electronic structure of MPBA/NH2@Pt/AgVO3 with its adsorption energy (−2.1 eV) has been scrutinized via density functional theory. Accelerated electron transfer (ks = 4.69 s−1) driven electrochemical oxidation of glucose sensor showed the higher detection limit (LOD) of 61.3 μM and the linear dynamic range from 0.05 to 22.0 mM. Glucose uptake assay of macrophage phenotypes between the healthy and insulin-resistant types provides an in-depth understanding of how glucose impairment affects the macrophage phenotypes. We also observed the M1-type macrophages have uptaken significantly larger amounts of glucose than the others (M0 and M2).

Thermophysical and adhesive properties of functional polymer materials based on epoxy resin and silicon-containing component

The work was aimed at developing an adhesive formulation with increased adhesive strength for metals. It contains an epoxy resin of the bisphenol type СHS-TROXY 520 (an analogue of ED-20), an amine hardener triethanolamine (TEA) and a silicon-containing component (3-isocyanatopropyl)triethoxysilane, designated as NCO-Si, with an optimal ratio of components. The content of NCO-Si in the formulations was 0.5, 1.0, 3.0 and 5.0 wt. %, respectively. The gradual transformation of the epoxy system into a three-dimensional network with the formation of ester and urethane groups was shown by IR spectroscopy method. Tensile and shear strength were determined using the tearing machine R-50 in accordance with current standards. It was found that the maximum values of physical and mechanical parameters were obtained when the amount of NCO-Si was 3 wt. %. The maximum values of adhesion strength to steel substrates δst. = 58.5 MPa significantly exceed those for neat epoxy formulations. The shear strength values for steel plates τst. = 21 MPa increase by 60 %, for aluminium plates they are δAl =14.5 MPa and increase by 48 %. The morphology of the samples has been studied by means of optical microscopy. It is shown that the modified NCO-Si samples are characterised by a phase-separated structure. At a minimum amount of NCO-Si (0.5 wt. %), structurally disordered spherical domains with a size of ~1÷3 μm are observed, an increase in the content of the organosilicon component leads to the formation of interconnected regular structures, which are less pronounced at 1.0 wt. % of NCO-Si and clear at 3.0 and 5.0 wt. % of NCO-Si. Thermogravimetric analysis (TGA) was performed as well. It is shown that the modification of epoxy resin by a silicon-containing component with NCO-Si groups leads to an improvement in thermophysical parameters, a decrease in internal stresses and the formation of a material with a structure close to equilibrium.

Effects of triglyceride and ethyl ester forms of EPA on hepatic lipid metabolism in mice with non-alcoholic fatty liver disease

In this study, the beneficial effects of EPA in ethyl esters (EE) and triacylglycerides (TAG) forms on high fat diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) were studied and compared. Results indicated that both EPA-TAG and EPA-EE can alleviate pathological features of NAFLD, such as hepatic lipid accumulation and lobular inflammation, with a more pronounced protective effects observed in EPA-TAG treated mice. The integrated hepatic transcriptomic, metabolic and gut microbiota profiles suggest that EPA-TAG and EPA-EE improved hepatic steatosis by suppression of food intake and lipogenesis, promotion of lipid and phospholipid PUFA remodeling, ketogenesis and fatty acids oxidation, possibly via activating the AMPK/adipocytokine signaling pathway. The protective effect of EPA was also associated with the regulation of intestinal flora structure. In general, EPA-TAG was found to be more effective than EPA-EE in preventing HFD-induced NAFLD by reducing appetite, improving hepatic lipid metabolism, increasing energy expenditure, and enhancing gut-liver cross-talk.

Discrimination between the Triglyceride Form and the Ethyl Ester Form of Fish Oil Using Chromatography-Mass Spectrometry.

Although the triglyceride form is the natural form of fish oil found in fish, the ethyl ester form of fish oil, which is used during processing to save costs, is also present on the market. In this study, fatty acids and lipids were determined using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-linear ion trap mass spectrometry (LC-LIT/MS), respectively, according to developed methods. The identification of fatty acids was based on the mass spectral characteristics and equivalent chain lengths. However, the fatty acid contents of both forms of fish oils are quite similar. The application of the LC-LIT/MS method for the structural characterization of triacylglycerols (TAGs) and the mechanism of LIT/MS fragmentation are also discussed. Neutral losses of CH2=CH2 (m/z 28) and CH3CH2OH (m/z 46), which are LIT/MS characteristics of ethyl ester from fish oil, were found for the first time. The triglyceride form of fish oils was easily and accurately identified using fingerprint chromatography. In conclusion, lipid analysis combined with LC-LIT/MS showed an improved capability to distinguish between types of fish oil.

In Vivo Absorption and Lymphatic Bioavailability of Docosahexaenoic Acid from Microalgal Oil According to Its Physical and Chemical Form of Vectorization.

Docosahexaenoic acid (DHA) is an essential fatty acid (FA) with proven pro-health effects, but improving its bioavailability is becoming a public health issue. The bioavailability of DHA from microalgal (A) oil has been comprehensively assessed, particularly in terms of the molecular structuring capabilities offered by A-oil. Here, we explored the impact of five DHA-rich formulas differing in terms of (i) molecular structure, i.e., ethyl ester (EE), monoglyceride (MG), or triglyceride (TG), and (ii) supramolecular form, i.e., emulsified TG or TG + phospholipids (PL blend) on the lymphatic kinetics of DHA absorption and the lipid characteristics of the resulting lipoproteins. We demonstrated in rats that the conventional A-DHA TG structure afforded more effective DHA absorption than the EE structure (+23%). Furthermore, the A-DHA MG and A-DHA emulsions were the better DHA vectors (AUC: 89% and +42%, respectively) due to improved lipolysis. The A-DHA MG and A-DHA emulsion presented the richest DHA content in TG (+40%) and PL (+50%) of lymphatic chylomicrons, which could affect the metabolic fate of DHA. We concluded that structuring A-DHA in TG or EE form would better serve for tissue and hepatic metabolism whereas A-DHA in MG and emulsion form could better target nerve tissues.

Insight into pyrolysis behaviors of cedar under different atmospheres via a fixed-bed reactor

Pyrolysis, as an efficient route for biomass, usually suffers the influence of pyrolysis atmosphere by the interaction with free radicals from biomass pyrolysis. To investigate the effects of pyrolysis atmosphere on cedar pyrolysis, several atmospheres including CH4, H2, CO2, CO, CH4/CO2 and H2/CO were used for CS pyrolysis on a fixed-bed reactor and the pyrolysis process was revealed based on products distribution, tar quality and compositions. The results show that the components in pyrolysis atmosphere apparently affect the distribution of pyrolysis products and play different roles in cedar pyrolysis. Tar yields under different atmospheres follow the order of H2/CO > H2 > CH4/CO2 > CO2 > CO > N2 > CH4. The highest tar yield of 45.5 wt.% was obtained under H2/CO atmosphere at 600 °C. Char yield was decreased under H2 by suppressing secondary reaction and followed the order of H2 < H2/CO < CH4/CO2 < N2 < CO2 < CO < CH4. The content of ketones was improved under CO2 atmosphere. The introduction of H2 mainly increases naphthalenes, benzenes, ketones and phenols; while the formation of acids, esters, aldehydes and furans was inhibited under CO atmosphere. Integrated process of biomass pyrolysis with CO2 reforming of CH4 can greatly increase tar yield and change tar compositions, which is ascribed to the participation of H-rich free radicals from CO2 reforming of CH4. This work provides a route to improve the yield of pyrolysis tar and adjust tar components.

Storage-stable and self-crosslinkable combinations of boronic acid containing polymers and diol containing polymers enabled by the latex system

Boronic ester is a kind of well-known and active dynamic covalent bond. Yet preparing an even boronic ester crosslinked network from boronic acid containing polymers and diol containing polymers remains challenging because the reaction between boronic acid and diol is so fast that by now blocking boronic acid/diol (in the form of boronic ester) or special mixing procedures are required. In this work, a series of storage-stable and self-crosslinkable combinations of boronic acid (2%, 4% and 8%, in mol%) containing polymer latices and diol (2%, 4% and 8%, in mol%) containing polymer latices were achieved by simply mixing the two types of latex dispersions, without using any blocking agents or special mixing procedure. In the combined dispersions, water as the dispersion medium isolates boronic acids and diol groups, while the combined latices can undergo self-crosslinking via the encounters of boronic acid and diols during the latex film formation. Target synthetic products were confirmed by NMR, UV–vis absorption, FT-IR and Raman spectra. The combined latices have simultaneously ensured the even mixing, storage stability (60 °C for 1 month or room temperature for 6 months) and self-crosslinking (examined by DMA, Soxhlet extractions, up to 97% gel content). The method of respectively preparing and then combining the two types of latices is better in polymerization stability, toughness, and wettability, compared to the method of preparing crosslinked polymer with the comparable divinyl boronic ester crosslinker (1%, 2% and 4%, in mol%). With these advantages, the method of combining such highly reactive polymers by utilizing the features of latex systems is inspirational in the fields of colloid science and reactive polymers.